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Thread: Interesting G-120 amp design...

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    Smile Interesting G-120 amp design...

    Hey folks... Someone forwarded this site to me. It's got details on a home-built scanner amp design that can drive the G-120's at 24K and still give solid results. Pictures on the site tell the story - they look great!

    Don't know how expensive they'd be to build, but my guess is that it would be cheaper to build these things vs trying to buy a pair of Turbo Track amps on E-bay. (Even if the Turbo Track amps can go up to 30K, these still look pretty good at 24K.)

    Anyone else ever see these? (Well, besides you, Brian! )

    Adam

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    Additionally, his name on pl is pishtak. I emailed him not too long ago and he was super nice, sent me the complete schematics, complete board layout in .pdf format as well as .brd and .sch.

    I remember him saying the parts were only about $50. As far as the boards go, that would be a different story. Small quantities from a manufacturer would be spendy and every time I have tried a double sided board, I have jacked it up (not to mention all the through board jumpers). I am ready to give this a try though. Anyone have any tips on double sided boards or moreover, a cheap manufacturer that would not charge an arm and a leg and first born for 10 pieces?
    Last edited by absolom7691; 11-01-2008 at 10:19.
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    There might be more to this, Buffo. I seriously doubt that he could get 8 degrees at 24K from an LM675T driven by only 20 volt rails. This is the kind of thing that I would have to see with my own two eyes...

    On the page he mentions using Showtacle software. I don't know that software very well, but I have seen in their advertisements something like "fixed 35Hz scan rate" as an attempt to try to prevent damage to scanners. Since I don't know Showtacle software, it makes me wonder if the scan rate can really be adjusted separately. It could be that this guy thinks he is scanning at 24K but really isn't...

    Anyway, if he will be present at a future LaserFreak meeting, that might be a time when I can see this with my own eyes, and also plug in our softare and do some additional testing...

    Bill

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    Leave it to Bill to pop high speed scanning bubbles with his good intentions to make sure we get what we pay for!!
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    Cool

    Glad you mentioned something about it, Bill. Was actually thinking about picking up a set of G-120's from Aron Bacs at FLEM just to play with this. But if you don't think it's a viable option, then I'll hold off. (After all, I already have enough projects on the back burner as it is... I don't need one that is destined to fail!)

    Adam

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    I am still going to try this. It won't be that expensive and it will give me a new project. I'll see what kind of speeds I can get. I'll mainly be using Spaghetti and LaserBoy since I am poor. I can send the rig to Bill for testing when completed.
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    Cool

    Cool Brian... Keep us informed of your progress!

    Adam

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    That is a fairly advanced g120 amp. It looks like a hybrid of a g660 by GSI, as far as the shutdown stuff is concerned, and a early cambridge.

    G660 was GSi's high end amp before minisax sumdiff etc, and was a standard for 15-20 years. What it lacks in speed it will make up in precision as unlike most web designs, it does use both sides of the position sensor.

    I'd look at subbing a LM3886 for the output stage for a bit more power and bit less heat, plus you could route the shutdown signal in to the lm3886s mute pin.

    Steve

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    Steve, for an LM3886 substitute, what would you recommend for supply voltage in this type of application?
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    Quote Originally Posted by absolom7691 View Post
    Steve, for an LM3886 substitute, what would you recommend for supply voltage in this type of application?
    The 3886 can handle plus minus 35 V

    Steve

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